COVID toes, newborn blue toes, and prepartum SARS-CoV-2 infection
Authors: Ya Bin Zhou, Zi Gang Xu
Journal: The Lancet (2023)

We appreciate Christoph Hochmayr and colleagues1Hochmayr C Auckenthaler M Fink F-M Kiechl-Kohlendorfer U Griesmaier E Differential diagnosis of blue toes in a newborn baby: might have been maternal infection with COVID-19?.Lancet. 2023; 401: e20Summary Full Text Full Text PDF PubMed Scopus (2) Google Scholar sharing a case of a newborn baby with blue toes. However, we disagree with the diagnosis given for this case. The term blue toe syndrome was first introduced in 1976, as a condition characterised by the sudden onset of acute pain and cyanosis in one or more toes2Karmody AM Powers SR Monaco VJ Leather RP “Blue toe” syndrome. An indication for limb salvage surgery.Arch Surg. 1976; 111: 1263-1268Crossref PubMed Scopus (121) Google Scholar and is now defined by the sudden appearance of blue or violaceous discolouration in one or more toes without any apparent trauma, serious cold-induced injury, or disorders that produce generalised cyanosis.3Hirschmann JV Raugi GJ Blue (or purple) toe syndrome.J Am Acad Dermatol. 2009; 60: 1-20Summary Full Text Full Text PDF PubMed Scopus (64) Google Scholar However, for the case shared by Hochmayr and colleagues, the lack of clinical signs of pain makes blue toe syndrome unlikely. On the basis of the clinical presentation and prepartum SARS-CoV-2 infection, we believe the patient should be diagnosed with SARS-CoV-2-associated chilblain-like lesions. SARS-CoV-2-associated chilblain-like lesions, also known as COVID toes, represent late manifestations of COVID-19 and are more often reported in children and young adults than adults.4Martora F Villani A Fabbrocini G Battista T COVID-19 and cutaneous manifestations: a review of the published literature.J Cosmet Dermatol. 2023; 22: 4-10Crossref Scopus (12) Google Scholar The exact cause is not yet clear, but it is thought to be related to inflammation caused by the immune response to SARS-CoV-2.5Gao JC Huang A Desai A Safai B Marmon S “COVID toes”: a true viral phenomenon or a diagnosis without a leg to stand on?.JAAD Int. 2022; 9: 1-6Summary Full Text Full Text PDF PubMed Scopus (3) Google Scholar Some patients have substantially elevated concentrations of type I interferon, similar to chilblains lupus.5Gao JC Huang A Desai A Safai B Marmon S “COVID toes”: a true viral phenomenon or a diagnosis without a leg to stand on?.JAAD Int. 2022; 9: 1-6Summary Full Text Full Text PDF PubMed Scopus (3) Google Scholar The condition typically resolves on its own within a few weeks, which is consistent with the clinical course of this patient. Furthermore, we believe there were problems in the management of this patient. Routine laboratory investigations for patients with blue toe syndrome should include a complete blood count, renal function tests, liver function tests, and urinalysis to identify various potential causes.3Hirschmann JV Raugi GJ Blue (or purple) toe syndrome.J Am Acad Dermatol. 2009; 60: 1-20Summary Full Text Full Text PDF PubMed Scopus (64) Google Scholar However, the patient only underwent a routine blood test among the mentioned investigations. In conclusion, while we appreciate the case shared by Hochmayr and colleagues, we believe that the clinical presentation suggests a diagnosis of SARS-CoV-2-associated chillblain-like lesions rather than blue toe syndrome. We declare no competing interests. Differential diagnosis of blue toes in a newborn baby: might have been maternal infection with COVID-19?A newborn baby girl with blueish-coloured skin lesions on the tips of the first, second, and fourth toes of her right foot was brought to our unit 12 h after birth (figure). Apart from the noted abnormalities, the patient was healthy; she was normally alert and showing no clinical signs of pain. The respiratory rate was between 40 and 50 breaths per min, oxygen saturation was over 95% on room air, heart rate was between 120 and 140 beats per min, and temperature was 36·5°C. No history of mechanical or physical damage and no familial predisposition to thromboembolic events or autoimmune diseases was reported. Full-Text PDF COVID toes, newborn blue toes, and prepartum SARS-CoV-2 infection – Authors' replyWe thank Ya Bin Zhou and Zi Gang Xu for their interest in our Clinical Picture1 and their critical considerations. Full-Text PDF